OP0215 IMMUNOME ANALYSIS INDICATES ROBUST INHIBITION OF PROINFLAMMATORY MEDIATORS UPON LEFLUNOMIDE-HYDROXYCHLOROQUINE COMBINATION THERAPY IN SJÖGREN’S SYNDROME: CXCR3 LIGANDS AS POTENTIAL INFLAMMATORY ENDOTYPE BIOMARKERS.
Authors: V. Baloche, C. Bogers, H. Leavis, J. Van Roon
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Primary Sjögren's syndrome (pSS) is a chronic autoimmune disorder characterized by lymphocytic infiltration and functional impairment of exocrine glands, resulting in dryness of the eyes, mouth and extra-glandular manifestations in numerous organs. Immunopathology in pSS is associated with prominent B cell hyperactivity reflected by elevated serum IgG levels, autoantibody production, immune complex formation, and complement activation [1]. In a recent double blinded placebo controlled randomized trial, we demonstrated unprecedented robust inhibition of B cell hyperactivity and different disease activity parameters (including primary endpoint ESSDAI) by leflunomide-hydroxychloroquine (LEF-HCQ) combination therapy in the treatment of patients with pSS [2]. <h3>Objectives</h3> To assess the potential of LEF-HCQ combination therapy to normalize dysregulated inflammatory cytokine levels in pSS patients, and to identify biomarkers that reflect inflammation, monitor changes in disease activity and predict the treatment response. <h3>Methods</h3> We employed a high-throughput protein Olink proteomic assay (Immuno-Oncology panel) in order to determine the blood serum concentrations of 92 immune biomarkers, assessed at baseline and at the clinical endpoint in placebo (n=8) and verum treated patients (n=21). Welch 2-sample t-test and paired t-test were used to calculate differences for unpaired and paired data, respectively and FDR corrected p values were assessed using the Olink Analyze package available on CRAN. <h3>Results</h3> Of the 92 immune biomarkers, 34 were significantly upregulated in pSS patients compared to healthy controls at the onset of the trial (all at least p&lt;0.05). Moreover, the majority of these inflammatory mediators (24/34) were downregulated after 24 weeks of LEF-HCQ treatment (LGALS9, CCL19, IL10, CXCL10, CXCL11, CXCL13, GZMH, CXCL9, and soluble CD28, CD83, CD27, PDCD1, ADGRG1, PD-L1, CRTAM) with 9 returning to healthy control levels (TNF, IL12, GZMA, and soluble LAG3, IL12RB1, TNFRS9/4-1BB, CD4, KLRD1, CD70). Conversely, no significant alterations were observed in the placebo group. Interestingly, changes in ESSDAI scores were significantly (all at least p&lt;0.05) associated with changes in IL13, TNF, PTN, CXCL9, CXCL11 and soluble LAG3 concentrations. In addition, changes in serum IgG and Rheumatoid Factor levels were both significantly associated with changes in soluble CXCL13, GZMA, CXCL9, soluble CD4 and CD28 concentrations. Based on a machine learning approach (sPLS-DA) we identified baseline levels of CXCL9/10/11 as key markers of the treatment response. <h3>Conclusion</h3> LEF-HCQ treatment robustly inhibits inflammatory activity in pSS patients. The correlation of several mediators with clinical activity parameters indicates that these may have value in monitoring the disease activity. Furthermore, the clinical outcome upon LEF/HCQ treatment seems predetermined by an inflammatory endotype, with circulating biomarkers such as CXCR3 ligands as key determinants. These findings represent an important advance in our understanding of the underlying immunopathology of pSS and could help in the development of more personalized and effective treatment approaches for pSS and potentially other rheumatic diseases. <h3>References</h3> [1]Mavragani CP, Moutsopoulos HM. Sjögren syndrome. CMAJ Can Med Assoc J J Assoc Medicale Can. 2014 Oct 21;186(15):E579-586. [2]van der Heijden EHM, Blokland SLM, et al. Leflunomide–hydroxychloroquine combination therapy in patients with primary Sjögren's syndrome (RepurpSS-I): a placebo-controlled, double-blinded, randomised clinical trial. Lancet Rheumatol. 2020 May;2(5):e260–9. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.